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People who swear by this kitchen trick often point to studies that back it up.
Expert perspective comes from Dwayne Mellor, who leads the Evidence-Based Medicine and Nutrition department at Aston University in the UK.
He says the theory behind the trend is sound, if a bit complicated. The health benefits are real, but smaller than many people expect.
What the Scientist Explained
During baking, moist dough full of air pockets turns into a soft, fluffy loaf. Oven heat and the water in the dough cause the starches in flour to expand and gelatinize, similar to what happens when flour thickens a sauce as it cooks.
Gelatinized starches are easier to digest, which makes it simpler for our cells to absorb the glucose (sugar) they contain. That’s especially true for many freshly made starchy foods, particularly those low in fiber or made from finely milled flour, like white bread.
Some scientists say this quickly available glucose contributes to a spike in blood sugar and insulin right after eating. Insulin helps cells use glucose for energy or store it, but excessive insulin can increase hunger and potentially lead to weight gain.
When a product cools significantly, its gelatinized starches can change form and become resistant starches, which are harder for digestive enzymes to break down. That makes the sugar in those starches harder to absorb, so resistant starches are less likely to cause a big blood-sugar or insulin spike after a meal.
The amount of resistant starch that forms depends on baking temperature and storage: fridge versus freezer. The rate of this change in the freezer is nearly twice as high as in the refrigerator, so more resistant starch forms in frozen bread, according to ScienceAlert.
Freezing also helps lock in moisture, so bread stays fresher and softer than it does in the refrigerator, where it tends to dry out and go hard.
So, Should You Freeze Bread?
Mellor discussed a study that tested freezing white bread and then toasting it. Ten healthy volunteers took part, and dietitians compared the effects of eating store-bought loaves with homemade bread.
For homemade bread, freezing and thawing reduced the rise in blood sugar by 31 percent over two hours. Toasting fresh bread lowered the glucose spike by 25 percent, Mellor noted.
The effect was stronger when homemade bread was frozen, thawed, and then toasted: blood-sugar rise fell by 39 percent. That could help blunt post-meal hunger, since frozen bread causes a smaller glucose and insulin spike.
The story was different for store-bought white bread: freezing it before toasting didn’t improve the body’s blood-sugar response. That difference likely comes down to how store-bought and homemade breads are made.
Subsequent studies have shown similar results, so the effect now appears consistent in lab conditions, Mellor says.
However, this benefit lasts only a few hours after you eat the bread.
So freezing bread before a meal can lower blood sugar during that meal — and might slightly affect the next one.
Resistant starch is harder to break down and also feeds microbes in the large intestine. That helps maintain a healthy balance of gut bacteria and supports metabolism.
Resistant starch may also help lower cholesterol, likely because gut bacteria ferment it into short-chain fatty acids. Lower cholesterol can reduce the risk of cardiovascular disease.
In short, freezing bread has potential health benefits, though they’re modest. Mellor also points out that freezing helps reduce food waste.
How to Properly Freeze Bread?
Use fresh bread that’s cool, not hot. Slice the bread into pieces. Place the slices on a board or plate and put them in the freezer. Once the slices are completely frozen, transfer them to a bag or container and seal it tightly.
Thaw the bread in its packaging at room temperature for several hours before eating.
